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Sunday, November 27, 2011

Mars Science Lab: Liftoff!

Yesterday morning, at 10:02 EST, NASA’s Mars Science Laboratory (MSL) took off from Cape Canaveral in Florida.  In my opinion, this is possibly the most exciting scientific event of the year, as this mission to Mars is carrying the new Mars rover, Curiosity.

Curiosity isn’t the first Mars rover, of course.  The first was the small rover Pathfinder, which spent nearly three months on Mars in 1997 and set the precedent for all following rovers.   Most people are probably more familiar with the Mars Exploration Rovers (MER), Spirit and Opportunity.  The MER twins landed on opposite sides of Mars in 2004, their mission to answer the big question: has there ever been permanent water on Mars?  In the time since their deployment, these rovers, along with the handful of other landers and orbiters we’ve sent to Mars, have uncovered astounding evidence of past Martian environments: geologic features that hint at ancient river beds, floods, and perhaps even oceans.  The resounding answer is yes, Mars used to have plenty of water.

And why do we care if Mars had water?  Because on Earth, water is the basis of all life.  If Mars had water at one point, could it also have had life like we have on Earth?  This is the underlying question in all Mars research, and it is the main objective of the Mars Science Laboratory mission.

The newest Mars rover, Curiosity.
Curiosity is quite a bit bigger than previous rovers (2,000 pounds and the size of a small car!), and it is armed with ten state-of-the-art scientific instruments that will allow it to study the Martian environment better than any previous Mars mission.  The team behind the MSL mission is composed of scientists from numerous fields of study and from all over the world.  The rover is set to land in Gale Crater, just south of the Martian equator, in August 2012.  The primary mission objective: Determine whether life could have existed on Mars.

How will this rover determine if there could have been life on Mars?

By studying the chemistry of Mars.
Several of Curiosity’s scientific instruments are designed to make detailed observations of the chemistry of the rocks, soils, air and ice on Mars.  There are a number of ways that chemistry can tell us about potential life on a planet.  For starters, all life on Earth is dependent upon a core set of elements: the big six – Carbon, Nitrogen, Oxygen, Hydrogen, Sulfur and Phosphorus – along with several other elements needed in small amounts, like Iron and other metals.  These are the elements that make up the important organic molecules on our planet: amino acids, proteins, DNA, etc.  They are the basic ingredients of life, and if they are, or ever were, present in abundance somewhere on Mars, then there could very well be potential for life.

What would life on Mars
look like, I wonder?
And once life does get established on a planet, it leaves its own chemical signal behind.  Here on Earth, life is so intertwined with the rest of the planet that a chemical analysis almost anywhere would yield signs of living things.  The air is full of oxygen from plants, carbon dioxide and methane from animals and bacteria, and other gases.  The soils pick up complex organic molecules from the secretions of organisms, or from the breakdown of dead creatures.  Previous exploration of Mars has confirmed the presence of methane in the atmosphere – this has scientists excited since some microbes on Earth are known to produce methane, although it can also be produced by geologic processes – and discoveries made by the Phoenix mission may indicate the presence of organic molecules in Martian soil, but so far nothing more conclusive than this has been determined.  Curiosity’s colossal chemistry set will allow the rover to pinpoint these chemical calling cards of life, if they are in fact present on Mars.

By studying the geology of Mars.
The history of a planet is written in its rocks.  An ancient environment, be it a river bed, lake, ocean, or desert, will form a characteristic sequence of rocks and minerals, which geologists can study today.  The same processes that form rocks on Earth – volcanic activity, sediment deposition in water, etc. – will form similar rocks on Mars.  After years of study, a wealth of evidence exists to support the presence of ancient rivers on Mars, and many scientists have even pointed out evidence of a prehistoric ocean on Mars as well.  Curiosity will be able to examine Martian rocks and characterize the minerals in the rocks and soils.  Understanding the components of these geologic formations will allow scientists to infer the ancient environments in which they were formed.  Documenting prehistoric environments will not only allow us to draw a map of ancient Mars, but it will give us some insight into where to look for signs of life.

This image shows some of the tempting geologic features of Mars' Gale Crater.
Gale Crater was chosen as the landing site for Curiosity in part because of its fantastic geology.  Numerous geologic formations exist in Gale Crater, including layers of clays and sulfates, which form in the presence of water; an alluvial fan of sediment, likely carried downhill by water; and a series of fractures filled with minerals deposits, left there when the fractures filled up with water in the past.  This diversity of geologic features will not only allow the rover to explore several ancient environments, but by studying sequential layers of rock preserved in the mountain of the crater, Curiosity will be able to study how the landscape changed over the life of the planet, and will give us some great insight into how landforms evolve on Mars, and how the surface of the planet came to be what it is today. 

Of course, geological analysis isn’t good for just looking into the past.  Some scientists have suggested that there may be permanent water just below the surface of the Martian soil, which may be a good place for microbial life.  Some of Curiosity’s equipment will allow it to scan below the surface for evidence of water.

By studying the atmosphere of Mars.
Curiosity is well-equipped to document the atmospheric conditions on Mars.  It will be able to read air pressure, air temperature, wind movement, and humidity.  All of this will allow scientists to characterize the weather patterns on Mars.  By throwing in chemical analyses, Curiosity will help us understand how certain gases – water vapor, carbon dioxide, or methane, for example – are cycled through the Martian atmosphere.  Understanding the nature of Mars’ weather and climate, and particularly how the atmosphere interacts with the ground and soils, is a big part of understanding the conditions life would have to endure on the planet.

On top of that, understanding the composition and activity of the atmosphere will allow scientists to come up with much more detailed models of how the Martian atmosphere was formed, and how it may have changed through time.  In concordance with the geologic studies, this will be a huge help in forming the prehistoric timeline of Mars.

The other aspect of the atmosphere that Curiosity will be investigating is surface radiation.  On Earth, a lot of the cosmic and solar radiation from space is caught by the atmosphere, but on Mars, the atmosphere is much thinner, and offers much less protection, and the surface of the planet is subject to much stronger radiation from the sun and elsewhere in space, as well as secondary radiation from the atmosphere and the ground.  Not only would strong radiation potentially hinder life on Mars, but it is also relevant to future missions.  One of Curiosity’s objectives is to help prepare for the future human exploration of Mars.  All of this information that is important for understanding Martian life will also be relevant when we start sending astronauts up to Mars.

This Atlas V rocket carried Curiosity up, up, and away.
So, is there life on Mars?

Well, first of all, Curiosity will almost certainly not answer that question directly.  Even if there is, say, microscopic life in the soil, the rover isn’t equipped to see it.  It is equipped to find evidence of that life, and once we have evidence, we can plan missions to look for life directly.

In my opinion, the odds of us finding modern life on Mars are slim, but we can remain hopeful.  After all, there could be water somewhere.  I personally think we are much more likely to find evidence of past life on Mars (I know, I know, leave it to a paleontologist…).  The current mission takes a lot of notes out of the paleontology book, looking for evidence of life in past environments, and I think that’s the right road to head down.  I will declare it right here on this blog, and if I am wrong, may a thousand evidences prove it: If we find life on Mars, it will be in fossil form, not living.

And if I am wrong, by all means, shout it from the mountaintops.  I won’t complain!

In any case, Curiosity is scheduled to touch down next August.  Assuming this Sky Crane set-up works (they’re using a brand new technique to land the rover on Mars.  Please work, Sky Crane.  Please don’t crash.  Man, it must be terrifying to work at NASA…), the rover will be making ground-breaking discoveries this time next year.  Keep your eyes open for Mars news; I know I will!

Mysterious red planet, here we come!

2 comments:

  1. Life on mars is not likely because water does not exist in liquid form and free oxygen is not present in sufficient quantity. The atmosphere of earth has 20 percent free oxygen whereas mars' atmosphere only has .15 percent free oxygen. This is not enough to sustain life as we know it.

    One of the possible places for liquid water to exist on mars would be in the subsurface. That would require higher temperatures as you go deeper into the crust. That is what happens in the crust of the earth, but not likely on mars. The temperature rises as you go deeper into earth's crust because of earth's molten core. One of the evidences of a molten core is the presence of a magnetic field. Mars hasn't had a magnetic field for billions of years, so that makes a warm subsurface unlikely. It is possible that life existed on mars in the ancient past because of the evidence for great quantities of water back then.
    The other reason why life probably doesn't exist is that the temperature in most regions never rises above the freezing point of water.

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    1. Those are great points, Tim. Life on Mars would definitely be tough. But just because Mars is so harsh and different from Earth doesn't necessarily preclude the possibility of life. Here on Earth there are organisms that are specialized for living places most things couldn't - in extremely high or low temperatures, or with extremely low oxygen, for example. These are called extremophiles. Scientists often study extremophiles to help them hypothesize what kind of life they might find elsewhere in the universe, including the nearby planet Mars.

      I wrote a post about extremophiles, actually!
      http://the-meniscus.blogspot.com/2011/06/in-unlikeliest-of-places.html

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